COLD-RESISTANCE AS AN ECOLOGICAL FACTOR IN THE GEOGRAPHICAL DISTRIBUTION OF CACTI.

The article discusses the cacti species' cold resistance and its geographical distribution. According to the study conducted by the Department of Botany at the University of Arizona in Tucson, Arizona, the geographical distribution of cacti, which are entirely adapted to a dry climate, is mainly dependent on the cold resistance of the species. It also says that not only cold resistance manifest itself for the new species occurring in the northern latitudes of the U.S. and Canada, but it determines the distribution of cacti at the higher altitudes proximity to the southern deserts where they are abundant. Furthermore, various species of cacti are also presented.